Strain gauge method for measuring polymerization contraction of composite restoratives

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Polymerization contraction in dental composites causes stress at the tooth-restorative interface.
• Understanding this contraction is crucial for durable and well-fitting dental restorations.
• Existing methods for measuring contraction may lack real-time capabilities.

Purpose of the Study:

• To introduce and validate a novel method using electrical resistance strain gauges for monitoring polymerization contraction in dental composites.
• To evaluate polymerization exotherm and contraction across different composite types and shades.
• To assess the suitability of the strain gauge method for real-time kinetic studies of polymerization.

Main Methods:

• Electrical resistance strain gauges were employed to measure polymerization contraction in real-time.
• The strain gauge system was calibrated using dial gauge measurements of gypsum product expansion.
• Three composite types (microfilled, hybrid, posterior) and various shades were tested under a 60-second curing cycle.

Main Results:

• The posterior composite (P-50) exhibited the lowest polymerization exotherm and contraction.
• The dark grey shade of Silux Plus showed significantly lower contraction compared to all other tested shades and materials.
• The strain gauge method provided reliable real-time data on the curing process.

Conclusions:

• Electrical resistance strain gauges offer a viable and precise method for real-time measurement of dental composite polymerization contraction.
• Material selection, specifically posterior composites and certain shades, can minimize polymerization-induced stress.
• This technique facilitates detailed studies into the kinetics of composite polymerization and stress development.